Re: [Harp-L] Re: The Reason that Overbends Work

[The Iceman <icemanle@xxxxxxx>]

some of this discussion reminds me of how piano strings vibrate.


The strings have a specific length. However, at the fixed points, the steel wire has a very short length that is really too stiff to vibrate, which becomes an issue only when getting to the higher notes on the piano, as the overall length is shorter and that small "dead area" becomes a larger % of the total vibrating string.



-----Original Message-----
From: Harmonicology [Neil Ashby] <harmonicology@xxxxxxxxxxxx>
To: Steve Baker <steve@xxxxxxxxxxxxx>
Cc: Harp-L <harp-l@xxxxxxxxxx>
Sent: Wed, Sep 24, 2014 9:42 am
Subject: [Harp-L] Re: The Reason that Overbends Work


Your input is always appreciated, but I would suggest the example of the tornado 
to witness the strength of the air at the point of focus (nearest the ground); 
the wedge-shape on the non-rivet side between the end of the slot and the 
reed-tip acts like some funnel [the tornado is also referenced as "funnel-cloud] 
and does focus to the airflow at the narrowest point; at the narrowest point 
then the air-speed or air-pressure must increase and that increase is indeed 
focused at the tip of the reed instead of evenly spread as in the closing 
direction.

As for the different effective length issue as you wrote then it should also be 
considered that the oscillation into the slot from the rivet side is blocked 
from the rivet to the start of the slot and therefore the slot length is 
effectively shortened equally on the rivet side.

/Neil Ashby II (" https://www.facebook.com/profile.php?id=100004575466934 ")


On â9â/â23â/â2014 at 5:22 PM, "Steve Baker" <steve@xxxxxxxxxxxxx> wrote:
>
>I don't believe it's a question of which point on the reed the 
>airflow is "focussed" on, airflow doesn't work like that. However, 
>the reason for the pitch difference may be that when the reed is 
>opening it's effectively slightly shorter due to the fact that 
>it's attached to the side of the reed plate away from where the 
>airflow is coming from, so its pitch is slightly higher. 
>Interesting discussion, thanks.
>
>On 23.09.2014, at 20:09, Harmonicology [Neil Ashby] wrote:
>
>> My theory pertaining to the overbend note being naturally higher 
>is as follows: Use for example the draw reed and to cause the 
>closing of the draw reed then the user is lowering the air 
>pressure on the side of the reed-plate away from the rivet; the 
>result is that the reed is actually pushed into the slot via the 
>higher air pressure which is evenly spread across the side of the 
>reed having the rivet; in the case of the overblow on the same 
>reed then the air-flow is focused at the tip of the reed at the 
>point that the reed is recessed into the slot and thus the air-
>pressure is focused into some small wedge-shape between the reed-
>tip and the slot; because the air-pressure is focused at that 
>small area then the reed vibrates as though it would be some 
>shorter reed.
>> 
>> /Neil Ashby II (" 
>https://www.facebook.com/profile.php?id=100004575466934 ")
>> 
>
>Steve Baker
>www.stevebaker.de
>www.european-music-workshops.com
>www.harmonica-masters.de